Manufacture of lubricating oils



Patented May 1, 1928.

UNITED STATES PATENT OFFICE.

FRANK W. HALL, 01 PORT ARTHUR, TEXAS, ASSIGNOR, BY MESNE ASSIGNMENTS, ToTHE TEXAS COMPANY, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

MANUFACTURE OF LUBRICATING OILS.

Ho Drawing.

This invention relates to the treating of hydrocarbon oils for thepreparation of lubricating oils and has special reference to themanufacture of cylinder oil.

Cylinder oils are usually manufactured from residual oils resulting fromthe reduction of crude petroleum by distillation with the aid of fireand steam. Such residual oil is commonly termed cylinder stock orcylinder stock residuum and the term cylinder stock is used herein withthat conventional meaning.

In the treatment of cylinder stocks, on account of the viscous nature ofthese oils as compared with less viscous lubricating oils, the ordinarymethods of treating hydrocarbon oils with chemical reagents cannot besuccessfully employed. It has been found difficult to properly treatcylinder stocks with sulfuric acid largely because of the difficulty insettling out or removing the acid sludge products of the reaction and onaccount of the refractory emulsions which are formed in the ordinaryneutralizing processes.

It has, therefore, been sought to refine cylinder stocks by firstdiluting the oil with a light petroleum distillate and then subjectingthe diluted oil to the action of the acid. This method of treating,however, has been very unsatisfactory due to the fact that there is aheavy loss in acid, since the acid reacts not onlywith the hydrocarbonsin the cylinder stock itself but also with the hydrocarbons of thelighter oil. An even more objectionable feature of this method ofprocedure resides in the character of the sludge products formed in thereaction. When the acid is applied to the mixed heavy oil and distillatethe resultant sludge is of a comparatively soft character and is highlysoluble in the oil mixture. The result is that the sludge does notreadily settle outof the oil.

The customary neutralizing methods in use in treating other kinds of oilare practically useless in treating these heavy oils. In fact theapplication of the usual alkaline solutions produces emulsions of such arefrac- Application filed October 5, 1923. Serial No. 666,707.

tory nature that it is common practice not to attempt to neutralize theacid-treated oil at all and merely to settle the oil for a time and thensubject it to distillation, to remove the light oil. This procedure,however, results in great deterioration of stills and vapor lines due tothe presence of the acid in the oil being distilled.

I have found that cylinder stock can be satisfactorily treated and thedifliculties above set forth avoided by treating the undiluted oil withacid and then adding a diluent to the oil. When the undiluted viscousoil is treated with acid a comparativel hard and tenacious sludge isformed whic is not readily soluble in a mixture of the cylinder stockand li ht oil so that whenthe light oil is added, a ter the acidtreatment, the greater portion of the sludge products readily settleout.

Furthermore, I have discovered that if the cylinder stock, aftertreatment with acid, be subjected to the action of a concentratedorsaturated alkaline solution that the oil may be satisfactorilyneutralized without the formation of the tenacious emulsions which areformed in previous methods of neutralizmg.

In order to fully disclose my invention I will now proceed to outline indetail the complete process of treatment which I have devised, thevarious novel features of which are set forth in the appended claims.

In practicing the invention a petroleum fraction, preferably a residueof petroleum distillation having a viscous nature suitable for cylinderoil, is subjected to treatment with a mineral acid, preferably sulfuricacid. The treatment may be carried on in an agitator or treating vesselof conventional design which it is unnecessary to describe herein. It isbest to add the acid to the oil slowly in order to prevent localizedburning of the oil. After the oil has been treated with the acid adiluent comprising a lighter oil, such as a hydrocarbon oil of thenature of naphtha, kerosene, or the like, is added and the oil anddiluent blown with air or otherwise thoroughly mixed. The mixed oil isthen allowed to stand for a time and the major portion of the acidsludge material is settled out of the oil.v

In the acid treatment a greater or less quantity of sludge materialtends to adhere to the walls of the vessel and for this reason it ispreferable to remove the oil after settling to another vessel. The oilis then treated with a concentrated or substantially saturated alkalinesolution, preferably a ,caustic soda solution. In common practice intreating hydrocarbon oils it has been considered necessary to employ,after the acid treatment, a quantity of neutralizin materialconsiderably in excess of the stoicIiiometric proportion required toneutralize the acid remaining in the oil and a weak or dilute alkalinesolution is always employed. I have found that in neutralizing the acidremaining in the oil, after my method of treating involving thetreatment of the 011 with acid and the subsequent dilution of the oil,that it is possible to effect neutralization by employing a quantity ofalkaline material substantially equivalent to the theoretical amountrequired for neutralization. After agitating the oil with the alkalinesolution the oil is allowed to settle for a time.

The oil is then agitated with pulverulent material which serves toremove the comparatively small quantity of entrained alkaline matterthat may remain in the oil. In thisstep of the process I prefer to usean inert material, such as fullers earth or the like. The mosteconomical material that I have used is fine fullers earth which hasbeen prepared by burning and grinding spent fullers earth that hadpreviously been used in filtering oils. After agitation with the fineclay the clay is settled out of the oil;

The treated oil is then removed to a still and distilled, preferablywith fire and steam, to remove the diluent and reduce the oil to theproper test. If a filtered cylinder oil be desired the oil may, prior tothe distillation, be filtered either by the percolation method or byagitating with fine clay and filtering through a filter press.

In order to more fully describe my invention a t pical instance thereofmay be given:,l000 barrelsof 600 fire cylinder stock is treated withabout 40 pounds per barrel of 98% sulfuric acid. The treated oil is thencut with a substantially equal volume of naphtha, the mixture blown withair and the acid sludge permitted to settle. The oil is then removed toanother vessel and agitated with about 3 barrels of concentrated causticsoda solution. After settling the oil is agitated with a small quantityof fine fullers earth. After settling out the earth the oil is removedto a still and distilled with fire and steam to bring it up to 600 F.fire test. It is to be understood that the the particular type of oilemployed and the particular product desired.

The process of my invention is greatly superior to other methods oftreating cylinder stock. A number of comparative experiments havedemonstrated that in treating oil in accordance with my invention about15 pounds of sulfuric acid will accomplish the same results as areobtained b about 40 pounds under prior methods of operation. Thecylinder oil produced is of a superior nature. For exam Ie, the carbonresidue as determined by the S. T. M. carbon residue test is much lowerthan is the case with cylinder stock treated by prior methods. Thecomparatively low carbon residue may be accounted for by the fact thatin my process of treatment the tarry products of the acid reaction arepracticall insoluble in the viscous oil and readily sett e out when thediluent is added, whereas when the mixed heavy oil and diluent aretreated with the acid, in accordance with prior methods, the sludgematerials formed are of a comparatively soft nature and are so freelysoluble in the mixed oil that they are not removed by any subsequenttreatment.

In many cases the acid products of the reaction are so completelyremoved by my process in which a diluent is added after the acidtreatment that it is possible to omit the treatment with the alkalinesolution and at the same time avoid in the final distillation treatmentthe excessive deterioration of the still equipment that ischaracteristic of present methods of operation. Thus the cylinder stockmay be treated with acid, then diluted with a lighter oil and themixture allowed to stand for a time so that substantially all 'of theacid products of the reaction are settled out. The oil is then subjectedto distillation, the acid content in the oil being so small that nomaterial convepience or deterioration of equipment resu ts.

Obviously many modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof, and therefore, only such limitations should beimposed as are indicated in the appended claims.

What I claim is:

1. The process of manufacturing cylinder oil which comprises treatingcylinder stock with sulphuric acid, adding a lighter petroleum oil tothe treated oil, permitting sludge materials to settle out from the oil,and treating the oil with a neutralizin material.

2. In the manufacture of cylin er oil the process which comprisestreating cylinder stock with sulfuric acid, diluting the treated oilwith a lighter h drocarbon oil and treatin the mixture wit aconcentrated alkaline so u'tion in quantity substantially equivalent ato the stoichiometric proportion required to neutralize the acidremaining in the oil.

3. In the manufacture of cylinder oil the process which comprisestreating cylinder stock with sulfuric acid, mixing the treated oil witha lighter petroleum oil and then 10 allowing the acid sludge materialsto settle out from the mixture.

In witness whereof, I have hereunto set my hand this 26th day of Sept.1923.

FRANK W. HALL.

